This invention relates generally to percutaneous electrical therapy systems for medical use. In particular, the invention relates to an electrode insertion pain reducer for use with a percutaneous electrical therapy system. The invention also relates to other features for minimizing patient discomfort during percutaneous electrode insertion.
Electrical therapy has long been used in medicine to treat pain and other conditions. For example, transcutaneous electrical nerve stimulation (TENS) systems deliver electrical energy through electrode patches placed on the surface of a patient""s skin to treat pain in tissue beneath and around the location of the patches. The efficacy of TENS systems in alleviating pain is questionable at best, however.
More recently, a technique in which electrodes are placed through the patient""s skin into the target tissue has been proposed. Percutaneous Neuromodulation Therapy (xe2x80x9cPNTxe2x80x9d) (also sometimes called Percutaneous Electrical Nerve Stimulation or xe2x80x9cPENSxe2x80x9d) using percutaneously placed electrodes achieves significantly better pain relief results than TENS treatments using skin surface electrodes. This therapy is described in Ghoname et al., xe2x80x9cPercutaneous Electrical Nerve Stimulation for Low Back Pain,xe2x80x9d JAMA 281:818-23 (1999); Ghoname et al., xe2x80x9cThe Effect of Stimulus Frequency on the Analgesic Response to Percutaneous Electrical Nerve Stimulation in Patients with Chronic Low Back Pain,xe2x80x9d Anesth. Analg. 88:841-6 (1999); Ahmed et al., xe2x80x9cPercutaneous Electrical Nerve Stimulation (PENS): A Complementary Therapy for the Management of Pain Secondary to Bony Metastasis,xe2x80x9d Clinical Journal of Pain 14:320-3 (1998); and Ahmed et al., xe2x80x9cPercutaneous Electrical Nerve Stimulation: An Alternative to Antiviral Drugs for Herpes Zoster,xe2x80x9d Anesth. Analg. 87:911-4 (1998). The contents of these references are incorporated herein by reference.
Thus far, PNT practitioners have used percutaneously placed acupuncture needles attached to waveform generators via cables and alligator clips to deliver the therapy to the patient. This arrangement and design of electrodes and generator is far from optimal. For example, the prior art has not adequately addressed the issue of how to reduce the pain and other patient discomfort accompanying percutaneous electrode insertion. It is therefore an object of this invention to reduce the pain and other discomfort experienced by the patient during insertion of percutaneous electrodes.
It is a further object of this invention to provide a percutaneous electrical therapy system having electrodes and electrode assemblies that are safe, efficacious, inexpensive and easy to use.
Other objects of the invention will be apparent from the description of the preferred embodiments.
The invention is a percutaneous electrical therapy system. In a preferred embodiment, the system includes a control unit; an electrode electrically connected to the control unit to deliver electrical therapy to a patient, the electrode comprising a sharp point at a distal end adapted to be inserted into a patient""s tissue at an electrode insertion point; and an electrode insertion pain reducer adapted to reduce pain experienced by the patient during insertion of the electrode into the patient""s tissue.
In some embodiments, the electrode insertion pain reducer includes a pressure element adapted to provide pressure against the patient""s tissue adjacent the electrode insertion point. The pressure element may surround the insertion point during insertion of the electrode.
In some embodiments, the pressure element includes an electrode introducer. The electrode introducer may further include an actuator adapted to provide pressure to the pressure element as it moves the electrode toward the patient""s tissue. There may also be a transmission assembly adapted to move the electrode""s sharp point a first distance when the actuator is moved a second distance, the second distance being less than the first distance.
In some embodiments, the electrode introducer has a distal face, the pressure element being adapted to extend beyond the distal face. The pressure element may have a first diameter, with the distal face having a second diameter greater than the first diameter. The distal face of the electrode introducer may be adapted to attach to the patient during electrode insertion.
In some embodiments, the system includes a patch adapted to be attached to the patient at the insertion point, the patch forming at least part of the pressure element. The pressure element may have an opening adapted to surround the electrode when the electrode is inserted.
In some embodiments, the system includes a housing in which the electrode is disposed prior to insertion, the housing being opaque.
The invention is also an electrode and an electrode insertion pain reducer as described above, apart from the control unit.
The invention is described in further detail below with reference to the drawings.